Generally discharges from on-site sanitation （OSS） system could be a source of pollution to the environment if not well managed. This work illustrates the potential of subsurface infiltration to treat secondary effl...Generally discharges from on-site sanitation （OSS） system could be a source of pollution to the environment if not well managed. This work illustrates the potential of subsurface infiltration to treat secondary effluent from a novel on-site vermi-biofiltration system called the Biofil Toilet Technology （BTT）. In practice, the BTT effluent is discharged via sub-surface infiltration. The focus of the research was to determine possible contaminant removal within the first 1.5 m depth of soil column. To achieve this objective, laboratory scale soil columns were designed and constructed for the treatment of secondary domestic wastewater from the BTT. Four different soil columns, each with 1.5 m depth of soil （sandy soil--SS, loamy soil--LS, clayey soil----CS, and red laterite soil--RLS） and fifth column with 0.45 m multi-layer sand filter were constructed and characterized. The columns were fed with the BTT effluent and sampled at ports spaced at 0.3 m, 0.8 m, and 1.5 m depths. Using the samples, parameters like COD, BODs, TSS, T-N, NO3-N, NO2-N, PO4-P, and pathogenic indicator microbes were monitored. RLS and SS columns efficiently removed COD, BODs, and TSS from the BTT effluent below the Ghana Environmental Protection Agency （GH EPA） guideline values. Up to 99% COD removal were observed in RLS column. A two to five log pathogen removal was recorded for the soil columns. The RLS and SS were found to have a high efficacy for contaminant removal with up to 80% of all contaminants being removed at a depth of 0.3 m along the soil columns. Thus the subsurface infiltration system can serve as a promising technology for the BTT effluent treatment. The study recommends the incorporation of infiltration systems to the BTT especially for areas with high water table or clayey soils.展开更多
In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds （VOCs） removal and filter bed pressure...In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds （VOCs） removal and filter bed pressure drop tmder varied inlet loadings. A laboratoryscale experimental biofilter for gaseous toluene removal was set up and operated for 100 days with inlet toluene concentration ranging from 250 to 2500 mg· m^-2 According to sensitivity analysis based on the model, the VOCs removal efficiency of the biofilter is more sensitive to Henry＇s constant, the specific surface area of the filter bed and the thickness of water layer, while the filter bed pressure drop is more sensitive to biomass yield coefficient and original void fraction. The calculated toluene removal efficiency and bed pressure drop satisfactorily fit the experimental data under varied inlet toluene loadings, which indicates the model in this study can be used to predict VOCs removal and bed pressure drop simultaneously. Based on the model, the effect of mass-transfer parameters on VOCs removal and the stable-run time of a biofilter are analyzed. The results demonstrate that the model can function as a good tool to evaluate the effect of biomass accumulation and optimize the design and operation of biofilters.展开更多
The focus of this experiment was to compare the treatment performance of nutrient and microbial reduction in granite （GR）, shredded polyethylene terephthalate （SP） and palm kernel shell （PKS） composites after so...The focus of this experiment was to compare the treatment performance of nutrient and microbial reduction in granite （GR）, shredded polyethylene terephthalate （SP） and palm kernel shell （PKS） composites after solid/liquid separation of blackwater. Laboratory tests were conducted on replicated specimens of the GR, SP, and PKS pervious composites and the mechanisms of microbial reductions and nutrient transformation in blackwater treatment investigated after filtration. Six cylindrical specimens measuring 1 l0 mm x 100 mm and made from the GR, SP, and PKS were used to determine the physical and hydrologic properties （density and permeability） of the specimens. Additional six pervious specimens measuring 0.3 m x 0.3 m ~ 0.05 mm were used for the solid/liquid separation of blackwater. Blackwater was first infiltrated through a layer of coir fibre and net lining and then run through each pervious composite specimen. Nutrient （ammonium, nitrate, nitrite, total nitrogen, and total phosphorus） and microbial （Escherichia coli and coliforms） analyses were conducted on the effluent from the specimens and compared. The GR, SP, and PKS particle sizes were seen to be uniformly graded and similar. The composite specimens did not have significant effects on the nutrient transformations and removal of organic matter but for total phosphorus. However, escherichia coli and other coliforms＇s growth were limited in the SP. Hydrophobic interactions between the SP composite and microbial cells of the microbes could have promoted attachment and limited their growth. It was observed that the mean pH in the effluent filtered through the composites was higher than in the influent partly due to the availability of calcium carbonate in the cement. The study suggests that the SP composite is a promising alternative to the GR composite for the reduction of microbial constituents in blackwater vis-a-vis its light-weight compared to the other pervious composites.展开更多
文摘Generally discharges from on-site sanitation （OSS） system could be a source of pollution to the environment if not well managed. This work illustrates the potential of subsurface infiltration to treat secondary effluent from a novel on-site vermi-biofiltration system called the Biofil Toilet Technology （BTT）. In practice, the BTT effluent is discharged via sub-surface infiltration. The focus of the research was to determine possible contaminant removal within the first 1.5 m depth of soil column. To achieve this objective, laboratory scale soil columns were designed and constructed for the treatment of secondary domestic wastewater from the BTT. Four different soil columns, each with 1.5 m depth of soil （sandy soil--SS, loamy soil--LS, clayey soil----CS, and red laterite soil--RLS） and fifth column with 0.45 m multi-layer sand filter were constructed and characterized. The columns were fed with the BTT effluent and sampled at ports spaced at 0.3 m, 0.8 m, and 1.5 m depths. Using the samples, parameters like COD, BODs, TSS, T-N, NO3-N, NO2-N, PO4-P, and pathogenic indicator microbes were monitored. RLS and SS columns efficiently removed COD, BODs, and TSS from the BTT effluent below the Ghana Environmental Protection Agency （GH EPA） guideline values. Up to 99% COD removal were observed in RLS column. A two to five log pathogen removal was recorded for the soil columns. The RLS and SS were found to have a high efficacy for contaminant removal with up to 80% of all contaminants being removed at a depth of 0.3 m along the soil columns. Thus the subsurface infiltration system can serve as a promising technology for the BTT effluent treatment. The study recommends the incorporation of infiltration systems to the BTT especially for areas with high water table or clayey soils.
基金This research is supported by the National Natural Science Foundation of China （Grant No. 51378286） and special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control （No. 11Y04ESPCT）.
文摘In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds （VOCs） removal and filter bed pressure drop tmder varied inlet loadings. A laboratoryscale experimental biofilter for gaseous toluene removal was set up and operated for 100 days with inlet toluene concentration ranging from 250 to 2500 mg· m^-2 According to sensitivity analysis based on the model, the VOCs removal efficiency of the biofilter is more sensitive to Henry＇s constant, the specific surface area of the filter bed and the thickness of water layer, while the filter bed pressure drop is more sensitive to biomass yield coefficient and original void fraction. The calculated toluene removal efficiency and bed pressure drop satisfactorily fit the experimental data under varied inlet toluene loadings, which indicates the model in this study can be used to predict VOCs removal and bed pressure drop simultaneously. Based on the model, the effect of mass-transfer parameters on VOCs removal and the stable-run time of a biofilter are analyzed. The results demonstrate that the model can function as a good tool to evaluate the effect of biomass accumulation and optimize the design and operation of biofilters.
文摘The focus of this experiment was to compare the treatment performance of nutrient and microbial reduction in granite （GR）, shredded polyethylene terephthalate （SP） and palm kernel shell （PKS） composites after solid/liquid separation of blackwater. Laboratory tests were conducted on replicated specimens of the GR, SP, and PKS pervious composites and the mechanisms of microbial reductions and nutrient transformation in blackwater treatment investigated after filtration. Six cylindrical specimens measuring 1 l0 mm x 100 mm and made from the GR, SP, and PKS were used to determine the physical and hydrologic properties （density and permeability） of the specimens. Additional six pervious specimens measuring 0.3 m x 0.3 m ~ 0.05 mm were used for the solid/liquid separation of blackwater. Blackwater was first infiltrated through a layer of coir fibre and net lining and then run through each pervious composite specimen. Nutrient （ammonium, nitrate, nitrite, total nitrogen, and total phosphorus） and microbial （Escherichia coli and coliforms） analyses were conducted on the effluent from the specimens and compared. The GR, SP, and PKS particle sizes were seen to be uniformly graded and similar. The composite specimens did not have significant effects on the nutrient transformations and removal of organic matter but for total phosphorus. However, escherichia coli and other coliforms＇s growth were limited in the SP. Hydrophobic interactions between the SP composite and microbial cells of the microbes could have promoted attachment and limited their growth. It was observed that the mean pH in the effluent filtered through the composites was higher than in the influent partly due to the availability of calcium carbonate in the cement. The study suggests that the SP composite is a promising alternative to the GR composite for the reduction of microbial constituents in blackwater vis-a-vis its light-weight compared to the other pervious composites.
